Switch Mode Power Supply Applications Research Articles

Analysis of the high-gain BOCUK DC-DC converter-based PFC using an LQR controller for SMPS applications

This research work emphasizes on the development of a unique high-gain BOCUK DC-DC converter for Switched Mode Power Supply (SMPS) applications. The high-gain BOOST-CUK (BOCUK) DC-DC converter combines the benefits of both Boost and Cuk converters for attaining instantaneous line current shaping and load regulation. The proposed BOCUK converter provides a non-inverted output and improves the voltage gain and efficiency. The modes of operation of the high-gain BOCUK DC-DC Converter in a Continuous Conduction Mode (CCM) with parasitic elements in the circuit are examined and a state-space model is constructed. The second-order model is derived using the Modified Hankel Matrix Method (HMM) to make the controller design easier. Dual-loop Control employing an inner Linear Quadratic Regulator (LQR) current Controller and an outer Atom Search Optimization (ASO)-tuned Proportional Integral (PI) controller is used to analyze the performance indices of the high-gain converter and fluctuations in line, load and setpoint are investigated. Simulation results prove that the LQR controller is robust in tracking the load voltage and provides excellent line current shaping with low % Total Harmonic Distortion (THD) and nearly Unity Power Factor (UPF). The hardware model for 200W is built and implemented using the TMS320F28027F microcontroller to verify the simulation results.

Improving Permeability of Ferrite Cores Used in Switch-mode Power Supplies

In this study two methods are proposed to increase the permeability of ferrite cores used in switch-mode power supply applications. The first method is based on the principle of magnetic shaking where an AC magnetic field is superposed on the magnetic core. This method yields good performance in shielding applications but still facing some technical difficulties in switch-mode power supply applications. The second method is based on superimposing a DC magnetic field component equivalent to the main DC component flowing in the main winding of the switch-mode power supply. This method is verified to reduce the power supply inductor current ripple by 68% while downsizing the core of the winding.

Effect of Firing Temperature on the Electromagnetic Properties of Electronic Transformer Cores Developed by Using Nanosized Mn–Zn Ferrite Powders

Current investigation deals with the effect of grain growth process as a function of sintering temperature on the electromagnetic properties (initial permeability, impedance, and gain) of Mn–Zn ferrite (MZF) cores (toroids). By employing auto combustion process, nanosized [(20 ± 5) nm] MZF powders were synthesized and toroid shape cores were obtained after subsequent calcination and firing (sintering) process. It was observed that the submicron structure (0.5 µm) achieved in the ferrite core sintered at 1,000 °C was gradually transformed into micron size grains by increasing the firing temperature i.e., 1,100, 1,200, and 1,350 °C. The results reveal that MZF core sintered at low temperature (1,000 °C) showed high impedance, low initial permeability, and narrow working frequency range i.e., 3–15 MHz. However, the improvement in initial permeability, sintered density, and operational frequency range (100 kHz–17 MHz) was observed at high temperature (1,350 °C) firing in the inert environment. This synthesized MZF core is more suitable for miniaturized switch mode power supply applications.

Modeling Microinductors With Thin-Film Alloy Magnetic Cores

This paper presents a compact nonlinear frequency-dependent circuit model for microinductors with magnetic thin-film cores. The model captures saturation, high-frequency eddy currents in the conductors and core, and capacitive effects. A modeling extraction algorithm is proposed that generates a passive and accurate circuit from current-biased small-signal impedance measurements. These measurements are wafer-level compatible and can readily be made using an impedance analyzer or vector network analyzer. The model is applicable to the most common microinductor topologies, including toroidal, stripline, and racetrack used for integrated power electronics applications. We demonstrate the model performance of these three different microinductor geometries with commercially available field solvers as well as actual device measurements for switched mode power supply applications. Field-solver simulations show that the model captures ac power loss significantly better than traditional models and captures the current waveforms within 4.5% error. Comparison of the model to device measurements results in an RMS error less than 7.1% in current waveform for a device transitioning in and out of saturation due to a 10-MHz rectangular pulse.

A Compact Physical AlGaN/GaN HFET Model

We introduce a physics-based compact model for AlGaN/GaN heterojunction field-effect transistors (HFETs) that is suitable for both RF microwave and switched-mode power supply (SMPS) applications, so that RF techniques can help determine HFET performance in SMPS applications. Such simulations can predict the on-resistance, slew rate, and breakdown voltage from the physical design of the transistor. Starting from an expression for the drain-source conduction current, charge distribution and displacement current are determined. The new model was implemented in Verilog-A and implemented in AWRDE, the design environment from Applied Wave Research. The HFET model was validated by comparison with Silvaco simulations and with data from an AlGaN/GaN HFET S-band amplifier. The new model accurately predicts device performance for dc, small-signal, and large-signal operations.

Flyback converter with novel active clamp control and secondary side post regulator for low standby power consumption under high-efficiency operation

Flyback converters are widely used in industrial and commercial products because of their advantages of simple structure and low cost. Energy and environmental conservation have prompted interest in high efficiency and low standby power consumption in switch mode power supply applications. However, it is difficult to satisfy both conditions simultaneously because of conflicting design considerations. A novel active clamp control method is proposed for improving power conversion efficiency and reducing standby power consumption in a flyback converter. In addition, an asynchronous-type secondary side post regulator is applied to the converter for minimising standby energy leakage and improving cross-regulation performance for a multiple output channel flyback converter. Operational principles, control schemes, switch stresses and power consumptions are analysed using a converter small signal model and mathematical equations of converter waveforms. The superiority of the proposed converter is verified using experimental results on 110 W prototype.

The method of double averaging: an approach for modeling power-factor-correction switching converters

This paper describes the modeling of power-factor-correction converters under average-current-mode control, which are widely used in switch-mode power supply applications. The objective is to identify stability boundaries in terms of major circuit parameters for facilitating design of such converters. The approach employs a double averaging procedure, which first applies the usual averaging over the switching period and subsequently applies generalized averaging over the mains period. The resulting model, after two averaging steps and application of a harmonic balance procedure, is nonlinear and capable of describing the low-frequency nonlinear dynamics of the system. The parameter ranges within which stable operation is guaranteed can be accurately and easily found using this model. Experimental measurements are provided for verification of the analytical results.

Novel soft-switching DC-DC converter with full ZVS-range and reduced filter requirement. I. Regulated-output applications

A novel soft-switching topology for DC-DC converters is proposed. It is well suited for applications in the range of a few hundred watts to a few kilowatts. It is essentially a hybrid combination of an uncontrolled half-bridge section and a phase-shift controlled full-bridge section, realized with just four switches. The main features of the proposed topology are zero-voltage-switching down to no-load without serious conduction loss penalty, constant frequency operation and, near-ideal filter waveforms. The improved filter waveforms result in significant savings in the input and output filter requirement, resulting in high power-density. The new topology requires two transformers and two DC-bypass capacitors. The combined VA rating of the two transformers is more than that of the single transformer of conventional full-bridge converters, for variable-input applications. In Part I of the paper, the converter operation is analyzed for typical switch-mode power supply applications, where the input voltage varies widely but the output voltage is fixed and is well regulated. Experimental results obtained from a 100 W/200 kHz proof-of-concept prototype confirm the superior features of the proposed hybrid configuration.

Voltage-injection control for switched-mode power-supply applications

As electronic systems become more complex, their power supplies require higher dynamic performance which is becoming increasingly difficult to meet. In many such applications the load is controlled by a supervisory control unit, so that a forthcoming load change can be anticipated. The paper proposes a new control method to enhance the dynamic response of power supplies that have a predictable load-switching pattern. By injecting a small voltage into the control loop in advance of the load application, it is shown that the dynamic response is greatly improved. Both experimental and simulated results are presented and demonstrate the robustness of the technique.

Coupled magnetic amplifiers in forward converter topologies

A voltage and current analysis of magnetic amplifiers in switch mode power supply applications is presented, and results are compared with those predicted by the analysis. The application of coupled magnetic amplifiers to power supplies with coupled inductors in their auxiliary outputs is given. Favorable results are obtained when control of the magnetic amplifiers is taken from the aggregate auxiliary output voltages.

PWM technique utilisation in the quasiresonant convertor

The quasiresonant forward convertor topology has a high power conversion efficiency due to the favourable switching conditions for the transistors and output rectifier diodes. In addition, this topology can employ output transformer parasitics in the resonant tank which makes it attractive for high voltage switched mode power supply applications. Unfortunately, a very broad range of operating frequency is required to control the output power, and therefore the highly efficient pulse width modulation (PWM) control technique in this resonant topology looks very promising. The adverse effects of the associated nonzero current turn-off switching can be reduced by using nondissipative snubbers. The resulting, PWM-controlled quasi-resonant convertor topology combines the advantages of both resonant power conversion and pulse width modulation techniques. The paper reports the analysis and PWM control characteristics of this hybrid convertor topology. An optimum operating mode of the quasiresonant convertor is identified and expressions for the optimum convertor parameters are derived. A 2.5 kW, 4 kV, 50 kHz convertor prototype for microwave heating was built to verify the analytical results.

Enhanced regenerative switching circuit for power transistors

The letter describes a novel combination of the conventional regenerative base drive circuit and the snubber circuit, which utilises the snubber current to accelerate the switching performance of a power transistor. The technique is particularly useful in high-frequency switch mode power supply applications.